Sun Dongdong, head of the university’s forensics department, told China Newsweek magazine (no relation to the American publication) that he thinks at least 99% of China’s petitioners are mentally ill, even if the vast majority of them do not show symptoms. He also expressed support for the forced hospitalizations of mentally ill petitioners.

“When [a petitioner] insists on his particular point of view, that point of view is a symptom of paranoia,” he said, according to the report (in Chinese).

“Hospitalization of [a mentally ill person] is the greatest safeguard,” he said. “He’s a danger to society and also a danger to himself. We must bring such a person in for treatment and speed up his mental recovery. In this way his human rights will be protected.”

Update 4/6/2009:
Since making those comments, Sun has submitted an apology. Part of the written apology, as posted on Sina:

Some of the content [of what I said in the magazine] was inappropriate, and brought forth controversy and misunderstandings. I deeply regret this. If some of the content hurt some people’s feelings, then I wish to extend my deepest apologies. I also truly hope that they [petitioners] would be able to go through legal channels to solve their issues.
其中一些内容因我语言表述不当，引起一些争议和误解，对此深表遗憾。如果因这些内容伤害了一些人的感情，在此我诚恳地向他们致以深深的歉意。也衷心的希望他们能够通过法定程序解决自己的问题。

Hundreds of mainland petitioners have condemned public claims by a prominent Beijing psychiatrist that “99 per cent of professional petitioners are mentally ill” and demanded he apologise for the remarks.

By late yesterday, 332 people nationwide, mostly petitioners and some former “patients” of the mainland mental-hospital system, had signed an open letter prepared by mainland-based Civil Rights and Livelihood Watch.

The letter described the comments by Peking University professor Sun Dongdong as shocking and irresponsible coming from a mental-health professional.

Protesters met at Peking University’s west gate today to protest Sun’s remarks. Below are photos and YouTube clips of protesters and police from Boxun: